Cardiac surgery, and more specifically traditional coronary artery bypass graft (CABG) surgery, has been performed since the 1970's on a regular basis with the advent of the cardio-pulmonary machine. In traditional CABG, the patient's heart is exposed by cutting through the patient's sternum and retracting the two halves of the ribcage. The heart is subsequently stopped while the blood continues to be pumped and oxygenated outside the body through extracorporeal circulation (ECC). The development of the cardio-pulmonary machine for ECC enables surgical interventions to take place on an arrested heart. This allows the surgeon to manipulate and operate on a perfectly still heart. As such, the arrested heart may be positioned to expose and provide the best access to the target artery requiring a bypass grafting.
However, there are two main invasive aspects associated to traditional CABG—the sternotomy incision and the ECC. Even with the constant technological improvements achieved during the last twenty-five years, the advantages offered with ECC have been at times offset by the morbidity (complications) and mortality related to the ECC itself. ECC has been documented to produce some well-known complications. Adverse effects associated with its use continue to be discovered and as such, ECC represents one of the most invasive clinical aspect associated with traditional CABG surgery. The inflammatory response, as well as the systemic microembolisms generated by ECC, induce to some extent a dysfunctional state of the brain, lungs, and kidneys, which tends to increase with the aging of the patient. Furthermore, evidence suggests that when ECC can be avoided, the left ventricular function (pumping efficiency) of the heart is better preserved, thereby also reducing the risks of postoperative complications and the need for ventricular assist devices to wean the arrested heart back to normal function. In addition to being one of the most invasive aspects of traditional CABG, ECC is also responsible for a large percentage of the initial procedure cost of traditional CABG. If ECC-related complications develop, ECC is also responsible for the post-operative costs incurred to treat these complications.
A median sternotomy, although less clinically-invasive than ECC, has the perception of being more invasive due to the surgical scaring that results from the surgery. A full median sternotomy may result in a temporary disturbance in the respiratory mechanism, an increased risk of operative shock or dehiscence, and re-operation surgery from bleeding complications. Moreover, prolonged exposure to air of the exposed mediastinum may lead to hypothermia, infection or compromise of the neuro-endocrine response. Patients with severe chronic obstructive pulmonary disease (COPD), severe emphysema or severe pulmonary insufficiency are therefore at a higher risk of developing complications when exposed to a sternotomy incision.
Port access surgery, developed largely by Heartport Inc. of Redwood City, Calif., consists of replacing the full median sternotomy by a series of intercostal port incisions in the patient's chest, through which coronary artery revascularization is performed. However, the most invasive aspect, ECC, is retained in this type of surgery. The patient's heart is arrested by occluding the patient's aorta preferably between the coronary arteries and the brachiocephalic artery with an expandable balloon on the distal end of an endovascular catheter which may be introduced via a femoral artery. Cardioplegic fluid is then delivered to the patient's myocardium through a lumen in the same catheter or through a separate catheter positioned in the coronary sinus. A series of cannulae and catheters are usually employed to divert the patient's blood flow to the cardiopulmonary machine and to return the oxygenated blood to the circulatory system while the aorta remains occluded to avoid backflow into the heart chambers and surgical field. The port access approach most often also requires lung deflation in order to improve the access to remote territories of the heart, such as the posterior coronary territory. Unlike traditional CABG, the longitudinal axis and apex of the heart cannot be “verticalized” with respect to the surgical table and retracted chest cavity tending to facilitate access to the posterior territory. Performing port access surgery remotely through a number of small ports tends to be difficult, at times leading to unwanted tissue dissection that requires the conversion to a full sternotomy in order to complete the surgical procedure.
In recent years, the drive for less-invasive and cost-effective surgical approaches and apparatus has placed emphasis on cardiac surgery as well. However, unlike other organ surgeries, gall bladder for instance, the beating motion of the heart tends to complicate the surgical intervention.
In minimally invasive direct coronary artery bypass graft surgery (MIDCAB), ECC is avoided and coronary artery revascularization is performed directly on the beating heart with the help of a mechanical coronary artery stabilizer, through a mini-sternotomy or mini-thoracotomy incision. This surgical approach allows access to only one or two of the anterior arteries of the heart, most commonly the left anterior descending artery (LAD). Demographically, only 5-15% of the cardiac surgery population is afflicted with single vessel disease; the majority of cardiac patients (70%) suffer from triple vessel disease, whereby at least one artery on each of the anterior, inferior and posterior territories of the heart requires a bypass graft. As a result, this approach has also been referred to as “limited access bypass surgery”. Moreover, the MIDCAB thoracotomy incision to access the beating heart has been discovered to be more painful and less tolerated by patients than originally anticipated, especially in younger patients.
More recently, the beating heart approach through a sternotomy incision has been adopted tending to facilitate positioning of the beating heart within the retracted chest cavity and tending to facilitate grafting of the difficult to access posterior arteries. Mechanical coronary artery stabilizers have been developed to immobilize a portion of the beating heart surface proximate to the target artery during the distal anastomosis phase of the surgery. A median sternotomy is desirable since it tends to allow the apex of the beating heart to clear the retracted ribcage as the heart's longitudinal axis is “verticalized” in order to expose the posterior coronary territory. In some patients, verticalization of a beating heart is not well tolerated and may lead to hemodynamic instability during the surgical procedure. At times, this unnatural “verticalized” orientation of the beating heart may be attained with some degree of atrial or ventricular distortion, and even some degree of valvular dysfunction and regurgitation. Moreover, although the beating heart approach achieves the elimination of the cardiopulmonary machine, the sternotomy incision with its associated complications is retained in this approach.
Percutaneous transluminal angioplasty (PCTA) or Coronary Stenting are intraluminal surgical procedures which achieve coronary artery revascularization through the enlarging of restricted vessels by balloon angioplasty (PTCA) and in some cases also supplemented by the scaffolding effect of the tubular mesh stent. Sternotomy incisions and ECC are avoided since the entire procedure takes place through the patient's artery. However, the high incidence of restenosis associated with PTCA, and its generally low endorsement in the treatment of triple vessel disease does not make this procedure suitable to the majority of cardiac surgery patients that require coronary artery revascularization. Other emerging technologies, such as Transmyocardial Revascularization (TMR) or Percutaneous Myocardial Revascularization (PMR) are reserved for surgically non-reconstructible coronary artery disease.
It would therefore be advantageous to have a surgical apparatus and associated surgical approach which maintains, as much as possible, the normal anatomic position and orientation of the heart during a surgical intervention. One aspect of the present invention aims to provide access to the posterior coronary territory of a beating heart during CABG surgery, without the need for a sternotomy incision, and while the longitudinal axis of the beating heart is maintained as much as possible in its natural, substantially-horizontal anatomic orientation. The combination of the beating heart approach with a surgical approach attempting to access all coronary territories without the need for either a sternotomy or thoracotomy incision would therefore offer distinct advantages in reducing the risk of complications and minimizing the surgical scaring normally associated with current CABG surgeries.
A percutaneous incision in the abdominal region below the patient's ribcage, and the subsequent creation of a trans-abdominal, trans-diaphragmatic tunnel may provide a suitable surgical approach to attain the patient's thoracic cavity. The patient's heart and internal cardiac tissue may then be accessed by a variety of surgical instruments extending through an access cannula placed in said trans-abdominal tunnel and extending beyond an anatomic barrier, such as the patient's diaphragm. A number of surgical manipulations and interventions may then be performed by selected surgical instruments on the target tissue such as the patient's heart or other internal cardiac tissue. Internal cardiac tissue includes but is not limited to the pericardium, epicardium, myocardium, endocardium, apex of the heart, ascending and descending aorta, vena cava, coronary arteries and veins, internal thoracic arteries, pleurae, endothoracic fascia, and other like anatomic tissue.
One aspect of the present invention describes a surgical apparatus that allows the manipulation and positioning of a beating heart within the patient's thoracic cavity, along with the deployment within the patient's thoracic cavity of coronary stabilizers that serve to immobilize a portion of said beating heart proximate to a target coronary artery, through a trans-abdominal tunnel. This aims to allow at least some surgical interventions associated with coronary artery revascularization to be performed without the invasiveness of ECC and without having to perform bone-cutting or bone splitting incisions such as sternotomy, intercostal thoracotomy with spreading of adjacent ribs, or other like surgical incisions. This tends to provide a closed chest surgical approach to perform cardiac interventions. The arteriotomy and distal coronary anastomosis, although may be performed through a number of intercostal ports not requiring the bone splitting or bone spreading incisions, are also preferably performed through the trans-abdominal, trans-diaphragmatic tunnel. In the present invention, the term “closed chest” will refer to surgical procedures which keep the patient's thoracic structure intact.
It is therefore an object of the present invention to provide a surgical apparatus and method that enable coronary artery revascularization on the beating heart without the need for ECC, and without having to spread apart the patient's thoracic bone structure through a sternotomy, thoracotomy or other like incision.
It is a another object of the present invention to provide a surgical apparatus and method that enable cardiac surgical interventions, not restricted to only beating heart CABG, to be performed without having to spread apart the patient's thoracic bone structure through a sternotomy, thoracotomy or other like incision.
Some of the aspects of the present invention may also apply to other types of surgery, such as laparoscopic, endoscopic, or thoracoscopic surgery, whereby surgery is performed on target tissue contained within an internal body cavity that is accessed by surgical instrument disposed through an access cannula. Here the manipulation of surgical instruments during a surgical intervention performed through an access cannula may be better effectuated if said instruments are engaged with an internal joint within said cannula. Also it may be desirable in such surgical procedures to be able to secure said joint and maintain engaged instrument in a desired fixed position and orientation relative to the access cannula, at least for a part of the surgical procedure. The surgical procedure may also be further improved if the access cannula is also engaged with a movable joint connected to a stable surgical platform, whereby said joint may also be secured by a tightening means to maintain access cannula in a desired fixed position and orientation relative to patient and surgical table. The access cannula may also serve to introduce into the internal cavity surgical aids which may not engage target tissue during a surgical intervention, but help facilitate a surgery through their installation. For example, a camera lens or a fiber-optic bundle to provide light.
It is a further object of the present invention to provide a surgical apparatus and method that tends to facilitate endoscopic surgery, more specifically endoscopic surgery where a surgical procedure is to be performed within an internal body cavity beyond an anatomic barrier, through the use of surgical instruments introduced therein through an access cannula.
These and other objects of the present invention will become apparent from the description of the present invention and its preferred embodiments which follows.